Hey hope this is the right spot for this type of question, sorry if it isn't.

I am departing St. John's YYT nfld to Toronto YYZ, then enroute to London Heathrow. My question is will i need to go through security again when I land in YYZ for my connecting flight to London Heathrow. The issue is refernece my carry-on, which may cause problems. It is a portable metal detector which I would rather not put in the back of the plane. The size is not an issue as it breaks down into 3 small pieces and fits into a regular carry-on bag. I guess that is probably 2 questions, thanks for any help